<template>
  <div>
    <router-link tag="div" to="/"  class="header-abs" v-show="showAbs">
      <div class="iconfont header-abs-back">&#xe624;</div>
    </router-link>
    <div class="header-fixed" v-show="!showAbs" :style="opacityStyle">
      <router-link to="/">
        <div class="iconfont header-fixed-back">&#xe624;</div>
      </router-link>
      景点详情
    </div>
  </div>
</template>

<script>
export default {
  name: 'DetailHeader',
  data () {
    return {
      showAbs: true,
      opacityStyle: {
        opacity: 0
      }
    }
  },
  methods: {
    handleScroll () {
      const top = document.documentElement.scrollTop || document.body.scrollTop
      if (top > 60) {
        let opacity = ((top - 60) / 140)
        opacity = opacity > 1 ? 1 : opacity
        this.opacityStyle = {opacity: opacity}
        this.showAbs = false
      } else {
        this.showAbs = true
      }
    }
  },
  activated () {
    window.addEventListener('scroll', this.handleScroll)
  },
  deactivated () {
    window.removeEventListener('scroll', this.handleScroll)
  }
}
</script>

<style lang="stylus" scoped>
  @import '~styles/varibles.styl'
  .header-abs
    position:absolute
    left:.2rem
    top:.2rem
    width:.8rem
    height:.8rem
    line-height:.8rem
    border-radius:50%
    background:rgba(0, 0, 0, .8)
    text-align:center
    z-index:600
    .header-abs-back
      font-size:.4rem
      color:#fff
  .header-fixed
    position:fixed
    left:0
    top:0
    right:0
    overflow:hidden
    height:$headerHeight
    line-height:$headerHeight
    color:#fff
    background:$bgColor
    text-align: center;
    font-size:.32rem
    z-index:600
    .header-fixed-back
      position:absolute
      left:0
      top:0
      width:.64rem
      height:$headerHeight
      line-height:$headerHeight
      font-size:.4rem
      color:#fff
</style>
